iPhone phone calls not working correctly

Here's the problem:

When I call someone I cannot hear the phone ringing and I cannot hear anything they're saying unless I put them on speaker. The person on the other end cannot hear anything I'm saying no matter what I do. Phone is about a year and a half old, dropped a few times but has a case on it. Also don't know if this matters, but sometimes when I plug my phone into my aux to play music in my car, the jack will be plugged in but music will still play out loud. In that case I restart my phone and its back to normal, I've tried restarting with the phone call issue but that doesn't work.